Energizing the future of batteries

By Dan Simmons and Laura L. OttoFebruary 26, 2018

The market for batteries is ever-growing. For lithium-ion batteries, it has surpassed $30 billion and is expected to double or perhaps triple by 2025. It also demands constant improvement in battery efficiency and storage capabilities. Answering this charge is a priority for UWM researchers, whose work in energy storage is helping power a strong industry cluster in Wisconsin and beyond.

Deyang Qu

UWM’s expertise got a boost in 2015 when Deyang Qu became the Johnson Controls Endowed Professor in Energy Storage Research. The endowment from Johnson Controls, a giant in the battery industry, funded a unique dry lab at UWM, the largest such facility at any North American university. Housed in the College of Engineering & Applied Science, the lab is a miniature factory, providing limited manufacturing of promising new batteries.

Today, the UWM Energy Advancement Center partners with several companies while researching battery science and developing next-generation power strategies. Among those companies is Milwaukee Tool, one of the world’s leading users of li-ion batteries.

UWM researchers attack the challenge from many different angles. Here are just a few of the ways they’re trying to take lithium-ion technology into the future.

UWM physicists have created a new hybrid material that dramatically boosts the energy storage capacity of lithium-ion batteries.

Professors Carol Hirschmugl and Marija Gajdardziska formed a startup company called SafeLi with the goal of breaking into a market hungry for improved lithium-ion batteries. Their graphene monoxide material would replace commonly used graphite in a battery’s anode, allowing for novel, lighter and safer anode materials that will charge faster and store more energy.

Lithium-ion batteries consist of a short stack of metal and plastic layers, with the positive electrode – the cathode – on one side, and the negative – the anode – on the back. Researchers call this sandwiched architecture a “jellyroll.” Add the electrolyte between the electrodes, and you have a lithium-ion battery in a pouch. The electrolyte carries positively charged lithium ions from the anode to the cathode and vice versa during charging or discharging, causing electrons to accumulate at the anode. These “free” electrons will return to the cathode along a wire that connects the electrodes, creating a current.

It has other advantages, too, because it can solve a problem with silicon-graphite, which has great potential as a next-generation material in anode research.

Adding about 10 percent silicon nanoparticles to the graphite anode doubles the battery’s capacity. But silicon massively swells and shrinks during charging and discharging, causing it to break up quickly. Graphene monoxide is a better match with silicon because it does not swell when it takes up lithium, and the new material’s flexibility compensates for the expanding silicon.

“Through Hirschmugl and Gajdardziska’s efforts, the mechanism of lithium insertion into graphene monoxide and silicon anodes will be understood, and that will help their startup remain competitive in this crowded market,” Qu says.

To learn how to think like entrepreneurs, the physicists, including team member Marvin Schofield, joined the Milwaukee I-Corps program. A partnership of five area universities, I-Corps trains academics how to turn ideas from lab research into products and startups. Administered by UWM and funded by the National Science Foundation, it’s the only I-Corps site in Wisconsin.

“I-Corps taught us how to get potential customers to tell us what is needed to gain a market share,” says Gajdardziska, who is also dean of UWM’s Graduate School.

Through I-Corps, the team met mentor Loren Peterson, an entrepreneur in UWM’s Lubar Entrepreneurship Center. They also met with top companies in the battery field, like locally based Johnson Controls. The researchers subsequently were accepted into the national I-Corps program in the Silicon Valley cohort, giving them access to people in companies like Tesla, Apple and Samsung.

Junjie Niu

Tin for the win?

In researching the batteries of the future, Junjie Niu thinks he’s found a winning combination of tin and a “super skin.” He’s exploring batteries that have a hybrid composite with tin – rather than graphite – as their anode material, paired with a protective and resilient skin made of titanium dioxide.

“You can use it for many years,” says Niu, an assistant professor of materials science and engineering. “Plus, you can charge your battery in 10 minutes or less.”

In trials, Niu’s team found their batteries have a capacity two to three times larger than the graphite anodes now used in more than 90 percent of lithium-ion batteries. Niu and postdoctoral researcher Shuai Kang have applied for a patent on the work.

Niu’s UWM team has attracted about $1.2 million in funding, both from within the UW System and from industry and government sources.

Beating the cold

All car batteries labor to start an engine during a deep freeze. But researchers in Qu’s lab have found a fix for the cold-car start – at least for electric vehicles, which use rechargeable lithium-ion batteries.

They’ve hit on the right recipe for the battery’s electrolyte. This liquid induces a chemical reaction to move lithium ions back and forth through the electrolyte during charging and discharging. That movement is necessary for generating a current.

“It isn’t the conductivity or the melting or freezing point of the electrolyte that has the largest effect on performance,” says researcher Joshua Harris. “It really all depends on the electrolyte’s components.”

From reactions with the electrolyte, a layer of oxidation builds up on the anode. If it grows too thick, it restricts movement of ions in the electrolyte, hindering the power. But if it’s too thin, it allows the electrolyte to continuously react with the electrodes, reducing battery life. The research team tested 46 different combinations of electrolyte components to find the ideal mix.

“This is one instance where we have developed the technology to solve the problem,” says Qu. “Now it’s up to companies to decide whether they want to invest to commercialize it.”